The present invention relates to an optical barrel, hereafter barrel, of the kind enclosing rod lenses of a rigid endoscope optics.
Rod lenses in endoscope optics serve as a relay system to transmit the image from a distal objective to a proximal ocular. A number of rod lenses are configured in a row and apart from each other. The endoscope optics is enclosed by a hermetically sealing cladding tube and includes a barrel within the cladding tube to keep the rod lenses accurately in place. The rod lenses must be sufficiently fixed in place within the barrel not to change their positions even when impacted in order to assure reproducible image transmission. The rod lens dimensions must be commensurately smaller than the barrel to allow axially displacing the lenses when the optical barrel is being assembled and, moreover, to preclude that slightly flexing the barrel should entail rod lens destruction.
To that end the rod lenses are only partly contacted by barrels of the above kind.
In a design of the above kind disclosed in German patent document DE 197 32 991 A1, rings are affixed to certain zones of the rod lenses, for instance at their ends, to brace the rod lenses against the barrel.
In a design of this kind disclosed in U.S. Pat. No. 4,148,550, the rod lenses are circular in cross-section though the barrel's cross-section is oval, as a result of which the rod lenses make contact along two lines with the barrel.
These known designs of the field being discussed entail elaborate manufacture and difficult assembly.